| In order to increase the ability to deal with emergency, all kinds of ships have madehelicopter as integral equipment, but the sway movements of ship produced by marineenvironment restrict the exertion of helicopter badly. Stabilizing platform is used to isolatethe ship’s movement and provide a relatively stable landing platform for helicopter, whichis of great strategic significance. The existing ship-based stabilizing platforms are difficultto realize dimensional stability, large-scale and heavy-duty. To overcome these limitations,the paper investigates the basic theory and experimental investigation of multi-axisship-based stabilizing platform with parallel structure. The main research contents are asfollows:(1) According to typical motion parameters of ship, the compensation ability indexesof stabilizing platform was defined, and the design principle of the task-oriented motionparameters of stabilizing platform was discussed. Based on the application requirement, a3-DOF parallel mechanism with coupling characteristic was synthesized; by defining theperformance indices of coupling characteristics, the effect of independent degree ofmechanism on kinematic performance was discussed. As to solve the critical problem ofStewart parallel mechanism, a6-PUS parallel mechanism which can be applied tolarge-scale and heavy-duty occasions was synthesized. By comparing with different typesof configurations, the final topology configuration of ship-based stabilizing platform wasdetermined.(2) Based on the screw theoretical basis of rigid dynamics, the acceleration adjointtransformation and adjoint mapping of multi-rigid-body system were derived. The motiontransformation relationship among bodies of the ship-based stabilizing platform wasdeduced, and the kinematics model of parallel ship-based stabilizing platform innon-inertial frame was built based on Lie bracket Jacobian matrix.(3) The inertia forces of component was analysised based on the rigid bodyacceleration Newton-Euler equation, and coupling dynamics model of of parallelship-based stabilizing platform in non-inertial frame was proposed. According to the adjoint transformation of multi-rigid-body accelerations, the kinematic problems in theprocess of aircraft approach glide down and landing were studied. A virtual prototypemodel of system was created with ADAMS software, and a contrast analysis was madebetween simulation results and theoretical computation results.(4) According to the characteristics of6-PUS parallel mechanism, a configurationparameters optimum design method based on the ship’s motion was proposed. With jointdisplacement as a goal of optimization, the structure parameters which fit practicalrequirement were received. By building slider axis’s multi-objective optimization modeland equivalent transformation of supporting rod’s motion, each joint axis of mechanismwas optimized. Through building the dynamics model of mechanism, the effect ofcounterweight on joint driving force was studied and the counterweight was optimallydesigned.(5) Through analyzing the impacts of sea status and weight of rods on dynamiccharacteristics, a strategy for dynamics model reduction in non-inertial frame wasproposed on the basis of the definition of the force impact factor. By introducing theequivalent motion parameters, the effect of coordinate system to the performance ofbranch input was studied, an equivalent simulation method for stabilizing platform basedon ground test was proposed.(6) The design process of the structure of each part and safety guards of the6-PUSparallel mechanism was introduced briefly, the control systems and human-computerinterface control were established, and the experiment prototype of ship-based stabilizingplatform was developed. On this basis the prototype ground testing was carried out; theperformance indicator of mechanism was tested and the correctness of mechanicalmodeling theory was verified. Finally, the feasibility of test prototype practically used inships was analyzed based on the theoretical calculation model. |
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